Type-writer escapement mechanism.



J TYPE WRF, J'. GHAPIN.

Patented Jan. l5, 1915.

Unrrar) sfrarns PATENT carica.

JOHN J. CHAPIN, OF DETROIT, MICHIGAN, ASSIGNOR- TO BURROUGHS ADDING MACHINE COMPANY, DE DETROIT, MICHIGAN, A CORPORATION OF MICHIGAN.

-TYPE-ITRII'ER ESCAPEMENT MECHANISM.

Specification of Letters Patent.

. Patented. J anj, 1915.

Application filed September 2, 1908. Serial No. 451,365.

-control the step byl step advance of the spring-drawn paper carriage.

The object is to provide an improved form of means for securing quiet and speedy action and capable of varying adjustments to divide the movement as best suited to the operator or if desired to have the entire .movement take place "in the downward stroke of kevs or space bar or the reverse, z'. e., the entire movement to take place upon the rise of keys or space bar. Furthermore provision is made'for advance of the carriage immediately setting in when vthe escapement starts its return to normal.

With these and incidental objects in view the invention consists in certain novel features of construction and combinations ofv parts the essential elements whereof are recited in the appended claims and a preferred form of embodiment of which is illustrated in detail in the accompanying drawings and specifically described hereinafter.

0f said drawings Figure 1 represents in sectionalized side elevation certain' portions of a typewriting machine including the escapement mechanism and connections'for operating the same.; Fig. 2 represents the escapement mechanism in rear elevation in normal condition; Fig. 3 is a somewhat similar view illustrating changed relations of parts due to depression of a key or the space bar; Fig. f1 is a detail cross section on the line lf-fl of Fig. 1; and Fig. 5 is a detail section on the line 5 5 of Fig. 2.

In said drawings the reference numeral 2 designates a key lever fulcrumed on the base framework 3 and upheld by a spiral spring 4. A universal bail underlies the keys, said ing arm 7 which is 'connected by a link 8 with the dependingarm of a bell crank 9 pivoted on a suitable standard and having a rearwardly-extending arm 10. The latter is coupled to an upwardly extending bar 11 connected by a spring 12 with an over-head portion of the framework 13. The upper end of -said bar is formed intoan eye through which extends a screw-threaded rod 14 carrying adjusting nuts 15 above and below said eye. Said rod connects with an escapement lever 16 of substantially bell crank form and coperating in a manner hereinafter described with an escapement wheel 17. The latter is loosely mounted upon a sleeve 18 (Fig. 1) which surrounds a,

shaft 19, the latter carrying a pinion 2O in mesh with the escapement rack 21 which is mounted upon the paper carriage in the usual orany suitable manner. The sleeve 18 and a second sleeve Q2 are supported by a suitable bearing 23 on the framework, said sleeve V22 carrying a plain roller 211 upon A Awhich a flange of the escapement rack rests.

There 'is secured to the rear end of the shaft 19 a drum 25 carrying a spring'- pressedpawl 26 (Fig. 4) which engages a ratchet wheel Q7 secured to the escapement wheel 17.

Reverting to the escapement lever 16 this is preferably composed of duplicate plates separated by suitable spacing collars and riveted together. It is pivoted at the angle of the bell crank to a bracket on the framework and carries pivoted between ears formed upon such duplicate plates a dog 30 connected by a light spring 31 with a screw stud 32. The latter engages a tapped opening in one of the rivets connecting the plates of the lever 16 and constitutes a back stop for said dog. rThe latter is formed with a beveled lip 33 which normally engages one of the teeth of the wheel 17 to hold the paper carriage stationary.

The pivot of the bell crank lever 16 is lo cated' substantially in a line tangential of the wheel 17 and embracing the end of the tooth which is normally bearing against the lip 33 and normally .the arm of said bell crank lever which carries this pivoted dog lies substantially horizontal as shown in Fig. 2. rl`he beforementioned rod 14 is hooked over a rivet of the lever 16 in this horizontal arm and it will be obvious that depression of a key lever, which through the connections already described draws down said rod 14, will thereby result in rocking the lever 16,'dr'awing the dog 30 downward. The other arm of. said lever stands normally about vertically and at the upper extremity carries a dog 35 which is clamped between the plates by means of a screw and a nut 37, see Fig. 5. This fixed dog isv in the shape of ya block which has an acting face 38 adapted upon movement of the lever 16, such as already mentioned, to move into the path 'of an approaching tooth of the wheel 17. Of course this fixed dog is to carry its acting face into such position `before the loose orpivoted dog 30 lets go the tooth 1t has been engaging. Now the upper arm of the lever 16 extends considerably beyond a horizontal plane embracing the axis of the escapement wheel and the location of the fixed dog is such that its line of traverse causes the acting face 38 to move toward and from the acting face of the approaching or engaged tooth. This acting face is formed on such an angle as to correspond with the l'ace of such approaching 4or engaged tooth as shownjin Fig. 3. Consequently, when the escapement lever starts to return the movement of the escapement wheel can at once set in for the acting face of the fixeddog is movingaway from the face of the engaged tooth. Meantime the pivoted dog 33, which under the impulse of its spring 31 has jumped pastthe normally engaged tooth, will move up into the path of the next tooth and stop the wheel when it has been released by the permanent dog.

Besides the-adjustment provided by the nuts 15 by which to determine the period of engagement between the key levers and the bail 5 6, adjustments are provided for both the loose dog andthe fixed dog. Mention has already been made of the screw stud 32 which constitutes an adjustable back stop for the pivoted dog. In addition to this the fixed dog is rendered adjustable by forming slots 40 in the plates of the upper arm of the lever 16 (Figs. 2V and 5) and a reduced portion of the block 35 fits one of these slots while a reduced portion of the nut 37 fits the other. Said slots extend in the line of movement of the fixed dog and provide vfor its adjustment at varying distances from the confronting tooth. Hence the dog can be adjusted to provide for stopping the es-l capement wheel at various points. Its extreme adjustment toward the wheel would cause it to prevent any appreciable advance of the Wheel upon depression of a key lever because bythe time the loose dog 'let go the normally engaged tooth the fixed dog would be against the confronting tooth. The other extreme adjustment of the' fixed dog and the extreme advance of the back stop stud for the loose dog would provide for practically the complete advance of the wheel taking place upon disengagement ofthe piv.- oted dog from the wheel, i. e., upon depression of the key lever. It Will'be obvious that various intermediate adjustments can be obtained according to what sort of action of the escapement mechanism may be desired. When the last-mentioned extreme adjustment is not employed but only a portion of the advance is to take place upon the rise of the key lever, such advance is not delayed until theI fixed dog disengages from the tooth ofthe wheel but starts immediately` upon release of the key lever as already explained. It will be seen therefore that the carriage gets well under way w hile the fixed dog is disengaging and any continued movement after the disengagement can be made extremely small so as to practically eliminate any shock or noise d ue to the encounter of the Wheel with the loose or pivoted dog. The latter is formed at its outer end on such an angle or curve as to instantly sna past the end of the tooth the moment the flzice of the lip 33 moves off the face of the tooth. A rivet 16 of the lever 16 constitutes a front stop for this pivoted dog holding the edge of its lip 33 at the circumference of the escapement wheel tooth as illustrated in Fig. 3. Further adjustmentis provided for by entering set screws 43 through studs 44 on.

the supporting bracket,` such set screws regulating the vibration of the escapement lever 16 whose end rivet 45 is adapted to abut 'said set screws. To facilitate disengagement of the dog lips from the teeth of the escapement wheel the acting faces of these teeth are made slightly tangential and not radial of the Wheel.

It will be seen that the above-described construction is well calculated to fulfil the ob jects primarily stated but it is to be understood that this construction is susceptible of modication within the scope of the inf vention.. I

' Vhat I claim is:

1. A typewriter escapement mechanism i comprising a toothed wheel, a bell crank having its pivot close to theperiphery of the wheel and havin its arms extending;v in opposite directions close proximity to the wheel, astepping pawl carried by one arm and engaging'the teeth of the wheel near the point of tangency with the wheel of a line drawn through the pivot of the bell crank and a. holding pawl on the other arm of the bell crank 'engaging the wheel at a point ma'- I terially beyond the'point of tangency with rom its pivot and the wheel of a line drawn through the pivot of the bell crank.

2. A typewriter escapement mechanism comprising a toothed wheel, a belll crank having its pivot close to the periphery of the wheel and having its arms extendin in opposite directions from its pivot an in close proximity to the wheel, a pivoted spring-held stepping pawl carried by one arm and engaging the teeth of the wheel near the point of tangency with the wheel of a line drawn through the pivot of the bell crank and a holding pawl on the other armv of the bell crank engaging the wheel at a point materially beyond the point of tangency with the wheel of a line drawn through the pivot of the bell crank.

3. A typewriter escapement mechanism comprising a toothed Wheel, a bell crank having its pivot close to the periphery of the wheel and having its arms extending in opposite directions from its pivot and in close proximity to the wheel, a stepping pawl carried by one arm and engaging the teeth of the Wheel near the point of tangency with the wheel ot a line drawn through the pivot of the bell crank and a holding pawl on the i other arm of the bell crank engaging the wheel at a point materially beyond the point of tangency with the Wheel of a line drawn through the pivot of the bell crank, said holding pawl adjustable 'substantially in the line of its movement.`

4. A typewriter `escapement mechanism comprising a toothed wheel, and a bell crank having its pivot close to the periphery of the wheel, one arm of the bell crank carrying a stepping pawl at the point of tangency to the wheel of a line drawn through the pivot of the bell crank and its other arm v carrying at a point beyond the point of tangency to the Wheel of a line drawn through the pivot of the lever a ixedly mounted dog with an acting face located to advance toward the face ot' the approaching tooth of the wheel to intercept the'same and in reverse rocking of the machine to recede from the face of said tooth permitting immediate movement of the wheel, said fixedly mounted dog being adjustable in the line of its movement toward and from the Wheel.

5. Atypewriter escapement comprising a' carrying on one side of its pivot a pivoted spring-held dog normally 1n engagement with a tooth of the wheel and on the other side of its pivot a ixedly mounted dog with an acting face located to advance toward of the lever to recede from the face 7. A typewriter escapement mechanism l comprising a toothed wheel and a bell crank pivoted close to the periphery of the wheel carrying on one side of its pivot, substantially at the point of tangency of a line from the pivot oitl the lever to the wheel, a

pivoted spring-held stepping dog and on the other side Iof its pivot at a point materially beyond the point of tangency of a line through said ivot to the periphery of the wheel a xed y mounted dog with an acting face located to advance toward the face of the approaching tooth ofthe wheel to intercept the same and in reverse rocking of the lever to recede from the face of said tooth permitting immediate movement of the wheel, said dog being adjustable on. the bell crank substantially in the line of its movement toward and from the wheelV and adjustable stops for the crank.

8. A typewriterV escapement mechanism comprising a toothed wheel, and a bell crank carrying on one side of its pivot a pivotedy spring-held dog normally in engagement with a tooth of the wheel and on the other side of its pivot a iixedly mounted dog with an acting face' located lto advance toward the face of the approaching' tooth of the wheel to intercept the same and in reverse rocking of the lever to recede from the face of said tooth permitting immediate movement of the wheel, said iixedly mounted dog being adjustable on the bell crank substantially in line of its movement, an adjustable back-stop for the pivoted dog, and adjustable stops for the bell crank.

9. A typewriter yescapement mechanism comprising a toothed wheel, and a bell crank carrying on one side of its pivot a pivoted spring-held dog normally in engagement with a tooth of the wheel and on the other side of its pivot a iXedly mounted dog with an acting face located to advance approximately in the line of advance of 'the approaching tooth of the wheel Vto intercept the same and in reverse rocking of the lever to recede from the face of said tooth approximately inthe line of movement of the latter permitting immediate movement of the wheel, said acting face of the dog corresporlding angularly with the face of the toot 10. A typewriter escape-ment mechanism one side of its pivot a loose dog sprn eld 4 r 32am to engage with the tooth of the Wheel, and approximately in the line of movement on the other side of its pivot a permanent thereof, permitting immediate movement of dog with an acting face located to advance the wheel- When the bel crank is vbrated. 10

approximately in the line of advance of the JOHN J. CHAPIN. approaching tooth 'of the wheel 'to inter- Witnesses:

pt the same, and in reverse rocking of the J. G. VIRGEN-rr,

lever to recede from the face of said tooth R. S. MIELERT. 

